Question About Avoiding Piezo Feedback Issues

I am currently building my 1st CBG and am planning to add a piezo pickup. I have read a bunch about piezos feeding back & what can be done to reduce it.

Would it be feasable to use a small circle of Dynamat rubberized audio sound dampening material attached to the back of the piezo, or covering/doming the back side but not touching it?

Seems like this would prevent sound waves from reaching the back side of the piezo which may help reduce feedback...maybe I'm way off base though. My concern is that it may interfere with the effectiveness of the piezo in some way. Any thoughts?

Replies to This Discussion

Try it. Don't confuse discussions about taming the top end or reducing unwanted handling noise with discussions re avoiding feedback tho...
If your amp is facing you and it's up loud it is going to feedback, it's inevitable.

I agree with the Phrygian Kid Amp placement is a major cause of feedback. Piezo pickups are very efficient giving a high output, and a lot of people make the mistake of connecting them to a regular guitar amp designed to work with magnetic pickups. These amps have high gain input stages that will go into oscillation ( feedback) when matched with the wrong pickup type.

Jay at tiny guitars makes his own bridge pickup with 2 20 mm piezo dishs on the bottom of the bridge held buy hot glue. I have owned a few of his builds that have that type of bridge pickup combo, never any feed back nomatter what amp I use.

I would go with two piezos wired in parallel this helps with the impedance matching to your amp.

I also glue the disks copper side down to the neck rather than the body and I also then glue a thin bit of wood over them covering the white crystal as best I can

All this seams to help a lot with feedback and makes the guitar viable for use on stage with a big PA

It depends what your using the guitar for really if you just noodling at home on a 5 watt amp you might not need to worry as much as if say you were using a marshal head double stacked on a 10 k rig every night on stage

Thanks for all the replys. I'm just fooling around at home & plan to build a 5-7 watt amp at some point...doubt I'd ever use anything larger. I'll probably be ordering a CB Gitty dual piezo setup w/passive vol pot...or something similarly simply to begin with.

Great thread, I just finished my second build and went with a single piezo disc (first build has a coil) and I do get humming when hooked into my big Fender amp. Plugged it into my little cigar box amp and the humming goes away so when I read what Dave said about big amps it all made sense, I started the 3rd, 4th, 5th and 6th builds (this is addictive) and I am going with parallel dual piezos, one with a coil and one with a rod piezo and see what goes. I'll let ya know. Thanks!

Piezos are screechy to begin with. You need to isolate the disc so that the sound waves coming from the amp have a hard time getting to the piezo disc. I glue mine to the underside of the lid with hot glue, and then smother the entire disc with hot glue to help insulate it. As already mentioned, they are prone to feedback to begin with, so all you can really do is tame them down a bit.

That is why some folks embed them inside a bridge/saddle so they are surrounded by wood on all sides.